Auto Popluate a dropdown field in my form to paste custom entry to a field and color match the field

Currently I have a support intake form that I am currently building for my company and we have a Sharepoint list that has a:

Screenshot 1

Recovery Time(RTO) dropdown field as seen below:

I also have a "Critical" field on the form that is currently a text field which I want to make this field autopopulate which ever dropdown item a user chooses from the Recovery Time Object (RTO) field and also color code based off the selection from the RTO field.

Screenshot 2

RTO Color Field:

Example of what I an requesting: if a user pick option "A" from RTO dropdown in the screenshot 1. above, it then places the selection RTO Rating in the Critical Field in red as High (Critical) as seen screen shot 2 above.

So for instance, if I select 0-8 Hours, the critical field will auto populate tthe text below for that corresponding RTO selection, so it will autopopulate "High Critical" and would color code it in Red. And if I select 8-24 Hours, it will autopopulate the text "Elevated".

And so on and soforth for the other selections.

I wish it could make the whole field turn the color of the selection king of like high light thewhole field in the sleection in the corresponding collors but not sure if that could be done, so the critical field would look like this:

(This is just a paint image to show what I want but if it cant be done, I am fine with that.)